[perl #122253] unknown attribute in Regex should not compile

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# New Ticket Created by  Elizabeth Mattijsen 
# Please include the string:  [perl #122253]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/Ticket/Display.html?id=122253 >


[13:33:31] <lizmat>      m: class A { has $.a = "a"; method b { 
"aaa".subst(/$!a/,"b") }}; say A.new.a; say A.new.b  # why isn't the .subst 
working ?
[13:33:32] <+camelia>    rakudo-moar 41574a: OUTPUT«a␤aaa␤»
[13:34:31] <lizmat>      m: class A { has $.a = "a"; method b { my $x = $!a; 
"aaa".subst(/$x/,"b") }}; say A.new.b  # putting it into a lexical first works
[13:34:33] <+camelia>    rakudo-moar 41574a: OUTPUT«baa␤»
[13:34:50] <lizmat>      rakudobug?
[13:35:55] <lizmat>     FROGGS, jnthn: ^^^
[13:36:47] <jnthn>       m: /$!foo/
[13:36:48] <+camelia>    rakudo-moar 41574a: 
OUTPUT«===SORRY!=== Error while compiling 
/tmp/GrGGxT5ir_␤Variable $!foo used where no 'self' is available␤at 
/tmp/GrGGxT5ir_:1␤------> /$!foo⏏/␤»
[13:36:56] <FROGGS>      m: class A { has $.a = "a"; method b { 
"aaa".subst(/"$!a"/,"b") }}; say A.new.a; say A.new.b
[13:36:57] <+camelia>    rakudo-moar 41574a: OUTPUT«a␤use of uninitialized 
value of type Any in string context␤baaa␤»
[13:37:21] <FROGGS>      that seems to be the runtime lexpad problem thingy 
masak++ had described in his blög
[13:37:35] <jnthn>       Um
[13:37:38] <Ven>         class variables are in lexpads ?
[13:37:49] <jnthn>       Wait...a regex is method-ish, and has its own self...
[13:37:56] <FROGGS>      eww
[13:38:16] <FROGGS>      m: class A { has $.a = "a"; method b { 
"aaa".subst($!a,"b") }}; say A.new.a; say A.new.b
[13:38:17] <lizmat>      aha... the plot thickens... rakudobug it ?
[13:38:18] <+camelia>    rakudo-moar 41574a: OUTPUT«a␤baa␤»
[13:38:24] <FROGGS>      yeah
[13:38:28] <FROGGS>     jnthn: is right
[13:38:56] <jnthn>       lizmat: Um, at this point all we  have is "it looks 
odd" rather than "it should do X"
[13:38:59] <FROGGS>      m: class A { has $.a = "a"; method b { 
"aaa".subst(/{say self}/,"b") }}; say A.new.a; say A.new.b
[13:39:02] <+camelia>    rakudo-moar 41574a: OUTPUT«a␤A.new(a => "a")␤baaa␤»
[13:39:16] <FROGGS>      I have no idea
[13:39:25] <FROGGS>      m: class A { has $.a = "a"; method b { 
"aaa".subst(/"{say self}"/,"b") }}; say A.new.a; say A.new.b
[13:39:27] <+camelia>    rakudo-moar 41574a: OUTPUT«a␤A.new(a => "a")␤A.new(a 
=> "a")␤A.new(a => "a")␤A.new(a => "a")␤aaa␤»
[13:40:02] <jnthn>       m: class A { has $.a = "a"; method b { 
"aaa".subst(/:my $ = say $!a; ./, b') } }; A.new.b
[13:40:04] <+camelia>    rakudo-moar 41574a: 
OUTPUT«===SORRY!=== Error while compiling 
/tmp/TCkwyckpg_␤Unable to parse expression in argument list; couldn't find 
final ')' ␤at /tmp/TCkwyckpg_:1␤------>  b { "aaa".subst(/:my $ = say $!a; 
./, b⏏') } }; A.new.b␤  …»
[13:40:13] <jnthn>       m: class A { has $.a = "a"; method b { 
"aaa".subst(/:my $ = say $!a; ./, 'b') } }; A.new.b
[13:40:15] <+camelia>    rakudo-moar 41574a: OUTPUT«(Any)␤»
[13:40:42] <lizmat>      m: say "aaa".subst(/a$/,"b")  # the reason I ran into 
this
[13:40:43] <+camelia>    rakudo-moar 41574a: OUTPUT«aab␤»
[13:40:51] <jnthn>       m: class A { has $.a = "a"; method b { 
"aaa".subst(/:my $ = say self.WHICH; ./, 'b') } }; A.new.b
[13:40:54] <+camelia>    rakudo-moar 41574a: OUTPUT«Cursor|139834212483800␤»
[13:42:13] <jnthn>       m: class A { has $.a = "a"; method b { 
"aaa".subst(/:my $ = say self.WHICH, $!a; ./, 'b') } }; A.new.b
[13:42:15] <+camelia>    rakudo-moar 41574a: 
OUTPUT«Cursor|139900812459976(Any)␤»
[13:42:21] <jnthn>       m: class A { has $.a = "a"; method b { 
"aaa".subst(/:my $ = say self.WHICH, $!pos; ./, 'b') } }; A.new.b
[13:42:22] <+camelia>    rakudo-moar 41574a: 
OUTPUT«===SORRY!=== Error while compiling 
/tmp/DBWEyB7Zo2␤Attribute $!pos not declared in class A␤at 
/tmp/DBWEyB7Zo2:1␤------>  $ = say self.WHICH, $!pos; ./, 'b') } 
}⏏; A.new.b␤    expecting any of:␤        postfi…»
[13:42:51] <jnthn>       m: class A { has $!dummy; has $.a = "a"; method b { 
"aaa".subst(/:my $ = say self.WHICH, $!a; ./, 'b') } }; A.new.b
[13:42:53] <+camelia>    rakudo-moar 41574a: 
OUTPUT«Cursor|140307760568368Cursor|140307760671904No such method 'gist' for 
invocant of type 'ParseShared'␤  in sub say at src/gen/m-CORE.setting:13805␤  
in method match at src/gen/m-CORE.setting:6280␤  in method subst at 
src/gen/m-CORE.setting:6355␤  in…»
[13:42:59] <jnthn>       Wow.
[13:43:22] <jnthn>       Yes, that's quite a mis-compile.
[13:43:36] <jnthn>       I know what it's doing.
[13:43:47] <jnthn>       I don't know we can make it DWLM though...
[13:43:57] <jnthn>       Because self in a /.../ thing really is Cursor
[13:44:13] <FROGGS>      L is for lizmat? :o)
[13:44:17] <jnthn>       Yes.
[13:44:27] <FROGGS>      true... and in a code somebody might really want the 
Cursor
[13:44:34] <jnthn>       Right
[13:44:35] <lizmat>      ok
[13:44:40] <jnthn>       Well, it's clearer with tokens and so forth.
[13:44:56] <jnthn>       All the same, we shouldn't compile it to stuff that 
looks up a random attribute on the wrong object. :)
[13:45:29] <lizmat>      I guess it should at least complain about it being an 
attribute that doesn't exist on the Regex ?
[13:45:38] <jnthn>       lizmat: Yeah.
[13:45:44] <lizmat>      so rakudobug it ?
[13:45:55] <jnthn>       Should just not compile
[13:46:06] <jnthn>       Yes, now we know the expected behavior, it's a 
resolvable ticket :)
[13:46:14] <jnthn>       So go for it :)